Piston ring



Dec. 23, 1941.

. 1 A; BowERs PISTON RING Filed Aug. 3, 1939 form improved oil controlrings.

Patented 23, 1941 -ThomasA.

Bowers, Boston, Masa, assignmto Power Research Corporation. Boston,Mass... a corporation of Massachusetts Application August a, 1m, SerialNo. 288,148 I (c zoo-4s) 2 Claims.

This invention relates to piston rings and more especially to coilcontrol rings formed from I strips of piston ring material.

-In a copending application, Ser. No. 276,503, filed May 31, 1939, Ihave referred to difllculties in eflfecting proper distribution of oilin worn cylinders by piston rings operating at high engine speedaand Ihave described and claimed ring structures fabricated from a length ofmetal ribbon devised to overcome these difllculties. In my earlierapplication a length of metal ribbon was first stamped or cut out toprovide relieved edges. The strip was thereafter reversely folded uponitself and compacted into an annular body in which the relieved edgescomprised oil scraping portions. It has now been found that im--provements may beeifected in stamped or out out 'ring structures byassociating together a pinrality of preform d w ll.

The chief object of this invention is to'provide improved ringstructures for effecting oil distribution on a cylinder wall, having inmind particularly means to overcome faulty oil distribution in cylinderswhich have become worn. It is a further object of the invention toprovide a simple, cheap and eillcient piston ring structure and methodof manufacture therefor, in which a plurality of preformed strips ofpiston ring material are arranged in novel manner to These and otherobjects of the invention will be readily understood from thefollowing'description when read in connection with me accompanyingdrawing and the novel features will be particularly pointed out in theappended claims.

In the drawing:

Fig. 1 is a perspective view illustrating a plurality of strips ofpiston ring material.

- Fig. 2 is a fragmentary plan view illustrating a step of preformingmaterial such as that illustrated in Fig. 1.

Fig. 3 is a fragmentary elevational view illustrating a preferredarrangement of preformed strips with respect to one another.

Fig. 4 is a fragmentary view in partial cross section illustrating afurther step of reversely folding the strips of material illustrated inFigs. 2 and 3.

Fig. 5 is a perspective view iragmentarily illustrating a finished ringresulting from compacting the folded material of Fig. 4.

Fig. 6 is another perspective view fragmentarily illustrating a modifiedtype of ring; and

Fig. 7 is a plan view of the ring illustrated in Fig. 5.

In accordance with my invention I provide a plurality of strips ofpiston ring material, as for example strips l and 2 as illustrated inFig. l. A preferred material for the strips will comprise a metal ribbonsuch as a steel ribbon, al-p th'ough other suitable substances may bedesired to be employed.

Along coincident edges of the strips i and 2, I form relieved portions 3and 4 cl strips 2 and 1 respectively. This may be eifected by somesuitable cutting operation, as for instance stamping, and preferably thestamping operation will furth'er form openings I and B at the innersides of the portions I and 4. These openings 5 and 8 facilitate bendingoperations effected on the strips as hereinafter described.

The strips l and 2 are then arranged so that the relieved edges .8 and 4are in an overlapping position as may be more readily seen in Figs. 2and 3.

In Fig. 4 I have illustrated a succeeding step rial, in whichthe twostrips are reversely iolded' upon themselves along lines of bending 1indicated in Fig. 2. The reversal-y bent structure is then compacted toform a ring body such as that illustrated in Fig. 5 and it will beobserved that the relieved portions of the strips i and 2 take alternateupper and lower positions such that they abut one another, with abuttingportions 4 disposed above the abutting portions 3, thereby forming upperand lower. oil scraping edges each of which includes two layers ofpiston ring material. The upper and lower edges l'orm outer contactingperipheries of a ring 8. Those portions of thestrips occurring directlyin back of, and coextensive with, the relieved portions 3 and 4 becomecrown forming portions Sin the finished ring I, while the portions ofthe strips occurring between the relieved portions 3 and I are angularlydisposed between tions 3 and l to comprise legs II.

By disposing the strips i and I so that relieved portions 3 and 4 occurin the offset position re-- ferred to and then folding the strips, itwill be seen that openings H between adjacent relieved portions occurout of alignment with one another, in a direction axially of. the ring,thereby sealing one another from passage of oil axially through thering. It is also pointed out that with the use of a plurality ofribbons, a plurality of scraping edges is present at both the top andbottom of the ring, which may more efllcient- 1y distribute oil on acylinder wall.

It will be observed that a length of material the relieved ,por-

formed into a ring such as that illustrated in Figs. 5 and 'I, will tendto have a uniform radial expansibility owing to the fact that upon beingclosed up upon itself at the several openings II, it will immediatelyrevert to its original position when released. This expansibllity ismade use of in confining the ring in a cylinder about a piston so thatit may tend to become expanded uniformly in all directions against thecylinder wall and thereby adhere to non-uniform or worn points in thecylinders, effecting greater efliciency particularly in high-speed motoroperation. Also, it is pointed out that all of the expansibility of thering acts through the scraping edges, which tends to make these portionsmore effective in properly adhering to the cylinder walls at all points.

A further advantage in utilizing the multiple ribbon arrangement toprovide oil scraping edges, consists in improved range of ring sizes.Increasing the thickness of one strip of piston ring material tends todevelop considerable increase in its wall pressure. However, the rangeor increased diameter through which such a thickened strip ring may beexpanded and still be effective is relatively small. Upon employing aplurality of strips 0! material, on the contrary there is secured lessincrease in wall pressure but the range through which such a wallpressure is eflective is greatly enlarged. This is important in that itfurther insures maintenance of the oil scraping edges against a cylinderwall under conditions such as those where a cylinder wall 1 has becomeworn out-or-round or worn tapered.

In either of these worn conditions referred to, the oil ring is requiredto be constantly expanded into larger diameters without too great aradial pressure such as would develop excessive wear.

It will be noted that the openings II which provide for the ring beingcompressible may, when included in a ring formed from a single strip ofmaterial, present minute passageways. However, by employing a pluralityof strips of material arranged in the overlapping manner shown anddescribed, it becomes possible to preserve the openings H for purposes01 compressibility and to seal them more completely to any passage ofoil urged through the ring in an axial direction for example by gaspressure.

In Fig. 6 I have shown a further modification of ring structure whichmay provide even further improved oil sealing by the use of three stripsof material formed in the manner already described to provide relievedoil scraping edges l2, l3 and I4. In this modification, it will be!noted that there is eflected a dovetailed arrangement by which one ofthe edges, as I3, is received between adjacent edges, as I2 and I4.Openings l5, l8 and I1 occur 'as described in connection with the ringstructure illustrated in Fig. 5 comprising spaces between abutting oilscraping portions oi respective strips. This figure is intended to beparticularly illustrative of the use of any plurality of ribbons whichmay be desired. It is again pointed out that increasing the number ofstrips employed increases the range of wall pressure of the ring. Theopenings between the oil scraping edges are more completely sealed bythe dovetailed arrangement shown and there are provided an increasednumber of oil scraping edges.

It will now be seen that I have provided an oil control ring having a.plurality 01 formed oil scraping edges at both the top and bottom sidesthereof. Additional means for preventing passage of oil axially of thering has been provided. Increased range of wall pressure has beendeveloped, and a novel step in a method of making piston rings fromribbon material has been set forth.

While I have shown a preferred embodiment of my invention, variouschanges and modifications may be resorted to in keeping with the spiritof my invention.

I claim:

l. A piston ring comprising spaced-apart sides, connecting portions forthe sides, said sides including a multiplicity of T-shaped segmentsarranged in spaced-apart relation, said T-shaped segments consisting ofa plurality of layers of piston ring" material superimposed one'uponanother, said multi-layer T-shaped segments being circumferentiallymovable with respect to one another, each of said multi-layer T-shapedsegments having a layer portion which overlaps a space between two otherlayer portions.

2. A piston ring comprising spaced-apart sides, connecting portions forthe sides, said sides including a plurality of contiguously arrangedT-shaped segments, each of said segments consisting of a plurality oflayers of piston ring material superimposed one upon another, saidmulti-layer segments being 'cir'cumferentially movable with respect toone another, and each of said multi-layer segments having a portionwhich extends circumferentially between spaced-apart portions of anadjacent multi-layer segment.

THOMAS A. BOWERS.

